This project consists of a neurophysiological and neuroanatomical investigation of the organization of the somatic sensorimotor cortex and its role in the generation and control of primate motor behavior. One of the central questions concerning the organization of the cerebral cortex is how inputs to a cortical region from a variety of cortical and subcortical sources combine to contribute to its output. We have chosen to concentrate on the percentral motor cortex (MI), known to project directly to spinal motor neurons, and those cortical areas in close functional association with MI, the supplementary motor cortex (MII); area 3a (a transitional region between MI and the postcentral somatic sensory cortex), and the premotor cortex (area 6). Two related approaches have been adopted for this project: (1) an analysis for the organization of peripheral inputs to the premotor cortex, MI, MII, and area 3a and (2) single unit studies of cortical areas which supply inputs to MI.